[PATCH 4.8 075/138] MIPS: KASLR: Fix handling of NULL FDT

[Greg Kroah-Hartman]

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Matt Redfearn <matt.redfearn@xxxxxxxxxx>

commit 4736697963385e6257ee8e260e97347e858cd962 upstream.

If platform code returns a NULL pointer to the FDT, initial_boot_params
will not get set to a valid pointer and attempting to find the /chosen
node in it will cause a NULL pointer dereference and the kernel to crash
immediately on startup - with no output to the console.

Fix this by checking that initial_boot_params is valid before using it.

Fixes: 405bc8fd12f5 ("MIPS: Kernel: Implement KASLR using CONFIG_RELOCATABLE")
Signed-off-by: Matt Redfearn <matt.redfearn@xxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Patchwork: https://patchwork.linux-mips.org/patch/14414/
Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/mips/kernel/relocate.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/mips/kernel/relocate.c
+++ b/arch/mips/kernel/relocate.c
@@ -200,7 +200,7 @@ static inline __init unsigned long get_r
 
 #if defined(CONFIG_USE_OF)
 	/* Get any additional entropy passed in device tree */
-	{
+	if (initial_boot_params) {
 		int node, len;
 		u64 *prop;